1. Technical Field
The present disclosure relates to the fabrication of microelectronic environmental sensors, such as gas composition sensors.
2. Description of the Related Art
Oxygen is one of the most important and abundant chemical species. It constitutes 21% of the earth's atmosphere, and is needed to sustain plant and animal life. Oxygen is also widely employed for industrial purposes. Conventional oxygen sensors are widely used in laboratory and industrial applications, wherever oxygen is consumed, emitted, or otherwise present. Such oxygen sensors, for example, those shown in FIGS. 2 and 3 below, generally have large scale form factors, tend to be expensive, and typically require involvement of skilled operators.
With the advent of micro-mechanical systems, deployment of sensors and feedback control systems in smaller scale applications is made possible. For instance, many electronic devices now contain environmental sensors. In one example, electronic thermostats connected to climate control systems rely on temperature sensors to trigger activation of furnaces and air conditioners. In another example, electronic weather stations rely on internal temperature sensors, barometric pressure sensors, and humidity sensors. Small scale consumer products such as motion activated air fresheners can make use of sensors that detect changes in ambient light, or changes in air flow.
Miniature sensors that are typically embedded on board mobile computing devices such as smart phones include, for example, magnetic field sensors used to determine orientation of the smart phone relative to the earth's magnetic field. Providing additional environmental sensors within smart phones, tablet computers, and the like may encourage program developers to create applications that otherwise might not be possible. In particular, if miniaturized gas sensors could be provided in consumer products, they might find wide use for medical applications such as pulmonary monitoring.